1908-9.] Vibrational Neutral Points in Magnetised Iron. 
17 
Intensity of Electric Oscillations. 
In the first part of this paper a very definite meaning could be attached 
to the intensity of the mechanical vibrations. It was found that their 
intensity varied with a function of the weight (W) of the ball and the 
distance (D) through which it fell, the function being approximately 
W x D 0-7 . With electric oscillations the same definite signification does 
not apply. It is assumed that the intensity of the resultant trains of 
damped oscillations in the secondary of the air transformer is increased or 
decreased as the number of 1 mm. sparks in series or the length of the 
single spark is increased or decreased. 
Diagrams. 
These are plotted from the experimental data in the way already 
described for mechanical vibrations, the intensity of the electric oscillations 
being represented by the number of 1 mm. sparks in series or the length of 
the single spark, for co-directional and transverse oscillations respectively. 
Field (H), induction (B), and induction change (dB) are likewise in 
C.G.S. units. 
Cyclic Field. 
Experimental Data. — In fig. VI. a b and fig. VII., with the twenty iron 
wires, (H)28 cms. diameter, inserted in oscillation solenoids Nos. 1 and 2 re- 
spectively, a series of ten trains of damped electric oscillations, increasing in 
intensity and co-directional with the magnetising field, are superposed in 
succession upon a sufficient number of points of that part of the normal 
hysteresis loop decreasing from H = 20, B = 8000 (cyclic extreme), to H — 0, 
B = 6900. The abscissae represent the number of 1 mm. sparks in series, 
increasing from one to ten, superposed in the case of figs. Vl.a b at six values 
of field, viz. H = 20, 1 7*3, 15T, 11*2, 7*8, and 0, and in the case of fig. VII. at 
eight values of field, viz. H = 20, 112, 7 - 8, 5*9, 4*4, 3'4, 2*0, and 0 ; the 
ordinates, the induction changes following thereon. 
Observe that for each value of field there are pairs of curves, represented 
in the case of each pair by the continuous and dash line curves respectively. 
Tables III. and IV. show how one of the pairs of curves in figs. Vl.a b (curves 
H — 15T) and in fig. VII. (curves H = 44) respectively have been obtained 
from the experimental data. If, when the field is positive, the connections 
between the secondary of the air transformer and the oscillation solenoid 
are not crossed, it is found necessary to reverse or cross them to obtain 
approximately the same readings when the experiments are repeated with 
negative field. On the other hand, if the oscillation connections are crossed 
VOL. xxix. 2 
